This invention relates to a mechanism for adjusting the angular position of an auxiliary cap relative to a main cap, the auxiliary cap and the main cap constituting the roof cap of a mine roof support unit.
A cap-positioning mechanism is used in a mine roof support unit of the type having an auxiliary cap (for example, a front extension cap) pivotally connected to a main cap. The auxiliary cap and the main cap constitute the roof cap of the unit, the main cap being supported above a floor sill by means of hydraulic props. The cap-positioning mechanism of such a unit includes a hydraulic ram attached to the main cap, and acting on the auxiliary cap.
A known type of cap-positioning mechanism has the hydraulic ram arranged immediately below the main cap. The piston rod of the ram engages a slide which is guided by means of slide blocks mounted in elongate recesses formed in the main cap. The front end of the slide is connected to the auxiliary cap by means of levers, the levers being pivotally connected to both the slide and the auxiliarty cap. The pivotal connections between the auxiliary cap and levers are positioned forwardly of the pivot joint connecting the auxiliary cap to the main cap. Such a cap-positioning mechanism is complicated and expensive. Moreover, it needs a hydraulic ram having a long working stroke. A mechanism of this type is described in DE-GM No. 1965204.
In another known arrangement, the auxiliary cap is constituted by a double-armed lever. One of the arms carries a plate to constitute the auxiliary cap, and the other arm is engaged by the piston rod of the ram. The ram is inclined, and its cylinder is fixed to the main cap. The disadvantage of this type of mechanism is that, owing to the inclination of its ram, a lot of the valuable space underneath the roof cap is occupied. A mechanism of this type is described in DE-GM No. 7020789.
The aim of the invention is to provide a cap-positioning mechanism which is simple, robust, and can be incorporated in the roof cap of a mine roof support unit in a space-saving manner.